Conventionally, classification and counting of particles contained in the sample such as blood and urine is performed. For instance, Japanese Laid-Open Patent Publication No. 2003-106984 discloses a particle analyzer for irradiating light on a liquid containing particles flowing while being surrounded by sheath solution, obtaining characteristic parameters from each particle, and generating a scattergram using the characteristic parameters. The particle analyzer classifies and counts the particles by classifying the particles appearing on the generated scattergram into a plurality of particle groups, and counting the particles of each particle group.
The particle analyzer disclosed in Japanese Laid-Open Patent Publication No. 2003-106984 determines classification abnormality of the particles appearing on the scattergram and displays the determination result on a display to prevent erroneous analysis, when measuring a blood sample containing nucleated red blood cells.
Japanese Laid-Open Patent Publication No. 2003-106984 describes that, in the blood sample containing the nucleated red blood cells, the nucleated red blood cells appear in a distribution region of the lymphocytes and in a region on the lower part thereof and does not appear in a distribution region of the neutrophilic leucocytes on the scattergram for classifying white blood cells into four classifications.
However, in the blood sample of a patient with a special disease, the nucleated red blood cells sometimes appear in a distribution region of the neutrophilic leukocytes or in a distribution region of the red blood cell ghosts (red blood cell particles after hemolysis) on the scattergram. Thus, in the particle analyzer disclosed in Japanese Laid-Open Patent Publication No. 2003-106984, the classification abnormality of the particles is not capable of be accurately determined when measuring the special blood sample in which the nucleated red blood cells appear in the distribution region of the neutrophilic leucocytes or in the distribution region of the red blood cell ghosts.